There have been relatively recent attempts by many detergent manufacturers to significantly improve the dissolution and dispensing performance of their granular laundry detergents. The approach many detergent manufacturers have focused on is the significant reduction in the level of, or even the complete removal of, water-insoluble builder, such as zeolite builder, in/from their granular laundry detergent formulations. However, due to the phosphate-usage avoidance legislation in many countries which prevents the detergent manufacturers from incorporating a sufficient amount of phosphate-based water-soluble builders, such as sodium tripolyphosphate, in their granular laundry detergents, and due to the lack of feasible alternative non-phosphate based water-soluble builders available to the detergent manufacturers, the approach many detergent manufacturers have focused on is to not completely replace the zeolite-based builder system with a water-soluble builder system having an equivalent degree of builder capability, but instead to formulate an under-built granular laundry detergent composition.
Whilst this under-built approach does significantly improve the dissolution and dispensing performance of the granular laundry detergent, problems do exist due to the significant amount of cations, such as calcium, that are not removed from the wash liquor by the builder-system of the granular laundry detergent composition during the laundering process. These cations interfere with the anionic detersive surfactant system of the granular laundry detergent composition in such a manner as to cause the anionic detersive surfactant to precipitate out of solution, which leads to a reduction in the anionic detersive surfactant activity and cleaning performance. In extreme cases, these water-insoluble complexes may deposit onto the fabric resulting in poor whiteness maintenance and poor fabric integrity benefits. This is especially problematic when the laundry detergent is used in hard-water washing conditions when there is a high concentration of calcium cations.
Another problem that needs to be overcome when the level of water-insoluble builders such as zeolite are significantly reduced in the composition, or when the zeolite is completely removed from the formulation, is the poor physical characteristics of the composition, especially after storage, which result in a poor cake strength.
The Inventors have found that the cleaning performance and physical characteristics of under-built detergent compositions is improved by carefully controlling where and how much hydratable material is incorporated into the under-built detergent composition in relation to alkyl benzene sulphonate.
U.S. Pat. No. 5,552,078 by Carr et al, Church & Dwight Co. Inc., relates to a powdered laundry detergent composition comprising an active surfactant, at least 70 wt % of a water-soluble alkaline carbonate salt, e.g. sodium carbonate, from 0.1 wt % to 2 wt % of a phosphate-builder, e.g. sodium tripolyphosphate, from 0.1 wt % to 2 wt % of a carboxylate polymer, and from 1 wt % to 12 wt % of water. It is alleged that compositions of U.S. Pat. No. 5,552,078 exhibit excellent cleaning and whitening of fabrics whilst avoiding the problem of eutrophication which occurs when a substantial amount of phosphate-builder is present in the composition, and while minimizing the problem of fabric-encrustation often present when the composition contains a large amount of carbonate builder. However, no details are given by U.S. Pat. No. 5,552,078 about the make-up of individual particles within the composition, and none of the detergent compositions exemplified by U.S. Pat. No. 5,552,078 comprise a hydratable material and alkyl benzene sulphonate.
U.S. Pat. No. 6,274,545 B1 by Mazzola, Church & Dwight Co. Inc., relates to a high-carbonate low-phosphate powder laundry detergent formulation which can allegedly be utilized in cold water fabric laundering with a minimized remainder of undissolved detergent residue in the wash liquor. The detergent composition of U.S. Pat. No. 6,274,545 B1 comprises an anionic/nonionic surfactant blend that is a partially sulphated and neutralized ethoxylated alcohol surfactant, and a polyethylene glycol ingredient, which allegedly increases the solubility of the laundry detergent solids in the wash liquor. However, U.S. Pat. No. 6,274,545 B1 does not give any details about how ingredients such as alkyl benzene sulphonate are incorporated into the composition in relation to any hydratable material, and none of the detergent compositions exemplified by U.S. Pat. No. 6,274,545 B1 comprise a hydratable material and alkyl benzene sulphonate.
WO97/43366 by Askew et al, The Procter & Gamble Company, relates to a detergent composition that comprises an effervescence system. WO97/43366 exemplifies a carbonate built bleach-free detergent composition. However, WO97/43366 does not give any details about how ingredients such as surfactant and hydratable material are incorporated into the composition.
WO00/18873 by Hartshorn et al, The Procter & Gamble Company, relates to detergent compositions having allegedly good dispensing performance and allegedly do not leave residues on the fabric after the laundering process.
WO00/18859 by Hartshorn et al, The Procter & Gamble Company, relates to detergent compositions allegedly having an improved delivery of ingredients into the wash liquor during the laundering process. The compositions of WO00/18859 allegedly do not as readily gel upon contact with water and allegedly do not leave water-insoluble residues on clothes after the laundering process. The compositions of WO00/18859 comprise a predominantly water-soluble builder system that is intimately mixed with a surfactant system.
WO02/053691 by Van der Hoeven et al, Hindustain Lever Limited, relates to a laundry detergent composition comprising greater than 10 wt % of a calcium tolerant surfactant, from 0.1 wt % to 10 wt % of a strong builder system selected from phosphate builders and/or zeolite builders, and less than 35 wt % of non-functional non-alkaline water-soluble inorganic salts. However, WO02/053691 does not give any details about how ingredients such as surfactant and hydratable material are incorporated into the composition.